The proposed research will examine the neurotoxic effects of low-level lead exposure during early postnatal development in rats. Emphasis will be placed on a functional analysis of a specific brain system damaged by lead poisoning. The hippocampus, a neural system known to be affected by lead poisoning and thought to be important in plumbism's neurological sequelae, was selected for study. Functional development of the hippocampus will be studied directly by electrophysiological techniques and indirectly by behavioral measures. Neurohistological methods will be used to examine the effect of lead on hippocampal morphological development and these data will be related to the results of functional testing. The neuropharmacological responsiveness of hippocampal neurotransmitter systems, as well as hippocampal seizure thresholds, will be compared in lead poisoned and control rats. The hypothesis that one mechanism of lead neurotoxicity may be displacement of zinc by lead at neural sites will be tested by determination of lead and zinc concentrations in the hippocampus and several other brain regions. An attempt will be made to modify the severity of the neurotoxic consequences of lead exposure by manipulation of dietary zinc intake.